import java.util.List;

public class MyLinkedList implements IList{
    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;
    public ListNode last;
    @Override
    public void addFirst(int data) {
        ListNode node =new ListNode(data);
        if (head==null){
            head=node;
            last=node;
        }else{
        head.prev=node;
        node.next=head;
        head=node;
        }
    }

    @Override
    public void addLast(int data) {
        ListNode node =new ListNode(data);
        if(head==null){
               head=node;
               last=node;
           }else{

            node.prev = last;
            last.next = node;
            last = node;
        }
    }

    @Override
    public void addIndex(int index, int data) {
        if(index<0||index>size()){
            throw new IndexException("双链表index错误"+index);
        }
        if(index==0){
            addFirst(data);
            return;
        }
        if(index==size()){
            addLast(data);
            return;
        }
        ListNode cur=findIndex(index);
        ListNode node=new ListNode(data);
        node.next=cur;
        node.prev=cur.prev;
        cur.prev.next=node;
        cur.prev=node;

    }
    public ListNode findIndex(int index){
        ListNode cur=head;
        while(index!=0){
            cur=cur.next;
            index--;

        }
        return cur;
    }

    @Override
    public boolean contains(int key) {
        if(head==null){
            return false;
        }
        ListNode cur=head;
        while(cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }

    @Override
    public void remove(int key) {
      ListNode cur=head;
      while(cur!=null){
          if(cur.val==key) {
              if(cur==head){
                  head=head.next;
                  head.prev=null;

              }else if(cur==last){
                  last=last.prev;
                  last.next=null;

              }else {
                  cur.prev.next = cur.next;
                  cur.next.prev = cur.prev;
              }
              return;
          }
          cur=cur.next;
      }
    }

    @Override
    public void removeAllKey(int key) {
        ListNode cur=head;
        while(cur!=null){
            if(cur.val==key) {
                if(cur==head){
                    head=head.next;
                    head.prev=null;

                }else if(cur==last){
                    last=last.prev;
                    last.next=null;

                }else {
                    cur.prev.next = cur.next;
                    cur.next.prev = cur.prev;
                }

            }
            cur=cur.next;
        }
    }

    @Override
    public int size() {
       ListNode cur=head;
       int count=0;
       while(cur!=null){
           count++;
           cur=cur.next;
       }
       return count;
    }

    @Override
    public void display() {
        ListNode cur=head;
        while(cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }

    @Override
    public void clear() {
      head=null;
      last=null;

    }
}
